1. Field of the Invention
The present invention relates generally to the field of appliances for correcting physical disorders such as foot drop and club foot, and more specifically to a resilient strap of plastic or spring steel secured at one end to the bottom of a shoe, extending from the front or side of the shoe and bent upward and back into an arc over the toe or side of the shoe, removably attaching to a harness secured around the lower leg, and exerting a force which tilts the ball of the foot up and toward the knee, thereby progressively stretching the necessary tendon to a length necessary to achieve a normal foot position and gait.
2. Description of the Prior Art
There have long been devices and methods for correcting the pathological contraction of the Achilles' tendon called foot drop and similar maladies. These have included surgery and physical therapy with appliances incorporating elastic bands and rigid casts for positioning the foot in a normal position. Such devices have generally been cumbersome, expensive, excessively painful and marginally effective.
One such prior device is that of Goffredo, U.S. Pat. No. 2,584,010, issued on Jan. 29, 1952. Goffredo teaches a strap which wraps around the ankle and has a loop on its front portion. An elastic cord is fitted through the eyelets of a shoe and through the strap loop and pulled tight enough to raise the foot out of the dropped position. A problem with Goffredo is that the amount of elastic tension which can be generated by a cord narrow enough to fit through a shoe eyelet is minimal. Thus Goffredo essentially just holds the foot up without stretching the achilles tendon and correcting the condition. Another problem is that Goffredo does not prevent the foot from tilting sideways.
Donzelle, U.S. Pat. No. 3,527,202, issued Sep. 8, 1970, presents a mattress and mattress enclosure for housing and providing care for a patient. Tensioned cords can be attached to the apparatus for positioning parts of the body, such as the foot. A problem with Donzelle is that it does not permit a patient to walk while in use, and so is unduly restrictive for a patient being treated only for drop foot. Donzelle is also prohibitively complex and expensive for such a limited treatment.
Schad, U.S. Pat. No. 3,986,501, issued on Oct. 19, 1976, discloses a rigid vertical member which wraps around the back of the calf of the user's leg, from the heel to the knee. A strap joins the top of the member to the leg. An adjustable elastic band extends from the upper portion of the member to the dorsum of a shoe, and hooks through a loop provided there. A problem with Schad is that the shoe and foot can twist to one side so that a proper corrective position is not achieved. Another problem is that elastic bands do not reliably generate steady, strong tension with prolonged use.
Heaney, U.S. Pat. No. 4,329,982, issued on May 18, 1982, reveals a device similar to Schad. One end of an elastic strap is secured to a looped harness encircling the top of the calf. The other end attaches to an off-center loop on the top of the shoe above the toe area. The off-center loop location only enhances the twisting problem of Schad, and the elastic band has the same shortcomings.
Deis, U.S. Pat. No. 4,566,447, issued on Jan. 28, 1986, teaches a device almost identical to Heaney. The Deis device includes a leg band which is secured to the leg just below the knee and an elastic ligament which extends from the leg band to an off-center loop on the toe of the foot or shoe. Deis presents the same problems identified for Heaney.
Marx, U.S. Pat. No. 4,790,300, issued on Dec. 13, 1988, discloses a device for correcting wrist drop. A pivoting rectangular frame is positioned over the top of the hand and attached to a harness mounted on the forearm. The frame is hinged on either side of the wrist and pivots coaxially with the wrist. Cords extend from the frame on either side of the hand and attach to the ends of an elongate member crossing the palm. An elastic member joins the top rear portion of the harness to the frame to pivot the frame upward and pull the hand up into a normal position. A problem with Marx is that the elaborate cantilever frame assembly would be relatively expensive to manufacture. Marx also shares the elastic band problems identified above.
Gyovai, U.S. Pat. No. 4,949,711, issued on Aug. 21, 1990, teaches a joint extension splint for the hand. A cast member is provided around the forearm and wrist and a supports a shaft member extending perpendicularly over the fingers. The shaft member is fitted with a pulley above each finger. A sling wraps around each finger and is attached to a cord which passes over the corresponding pulley and back to an independent coil spring secured to the cast member. In this way each finger is pulled upward and into a desired position. A problem with Gyovai is that it does nothing for wrist drop, but merely lifts the fingers. The cast may hold the wrist in a normal position, but provides no corrective tensioning. Gyovai would also be expensive to manufacture.
Pettine, U.S. Pat. No. 4,955,370, issued on Sep. 11, 1990, reveals a device for rehabilitating the Achilles' tendon following surgery to correct foot drop. A rigid circular loop surrounds the calf and is pivotally connected by two strut members to a shoe support platform. A spring-loaded member connects the front of the platform to the upper portion of one of the strut members. In this way, the front or toe portion of the platform, and of the shoe on the platform, is resiliently lifted up toward the knee of the user. A problem with Pettine is that the frame apparatus is relatively expensive to build. Another problem is that the shoe may slide out of position on the platform.
It is thus an object of the present invention to provide a training appliance which creates a tendon stretching force which can be varied a within a range of tension, and which can be provided with tension force ranges tailored to the needs of a specific patient.
It is another object of the present invention to provide such an appliance which prevents the ankle joint from twisting to one side.
It is still another object of the present invention to provide such an appliance which accomplishes its corrective purpose with a minimum of discomfort.
It is finally an object of the present invention to provide such an appliance which is simple and durable in construction and relatively inexpensive to manufacture.